Hierarchical Si/ZnO trunk-branch nanostructure for photocurrent enhancement

Abstract

Hierarchical Si/ZnO trunk-branch nanostructures (NSs) have been synthesized by hot wire assisted chemical vapor deposition method for trunk Si nanowires (NWs) on indium tin oxide (ITO) substrate and followed by the vapor transport condensation (VTC) method for zinc oxide (ZnO) nanorods (NRs) which was laterally grown from each Si nanowires (NWs). A spin coating method has been used for zinc oxide (ZnO) seeding. This method is better compared with other group where they used sputtering method for the same process. The sputtering method only results in the growth of ZnO NRs on top of the Si trunk. Our method shows improvement by having the growth evenly distributed on the lateral sides and caps of the Si trunks, resulting in pine-leave-like NSs. Field emission scanning electron microscope image shows the hierarchical nanostructures resembling the shape of the leaves of pine trees. Single crystalline structure for the ZnO branch grown laterally from the crystalline Si trunk has been identified by using a lattice-resolved transmission electron microscope. A preliminary photoelectrochemical (PEC) cell testing has been setup to characterize the photocurrent of sole array of ZnO NR growth by both hydrothermal-grown (HTG) method and VTC method on ITO substrates. VTC-grown ZnO NRs showed greater photocurrent effect due to its better structural properties. The measured photocurrent was also compared with the array of hierarchical Si/ZnO trunk-branch NSs. The cell with the array of Si/ZnO trunk-branch NSs revealed four-fold magnitude enhancement in photocurrent density compared with the sole array of ZnO NRs obtain from VTC processes.

Effect of ammonia on morphology, wettability and photoresponse of ZnO nanorods grown by hydrothermal method

“…As the adsorption and photodesorption processes are slow, the photocurrent reaches the saturation value very slowly. The slow photoresponse for the ZnO nanostructure was also observed and reported by other researchers [32][33][34]. In our case, according to the PL spectra of ZnO nanorods, the slow photoresponse may be attributed to the structural point defects.…”

Ultrathin‐Branched Pt Grown on Quasi‐Sphere Pd with Enhanced Electrocatalytic Performances

“…Among them, branched nanostructures are particularly attractive and important because their branches can provide many kikes and unsaturated atoms. Such structural feature can highly increase their specific areas and thus show a high activity ,. For example, El‐Sayed and co‐workers demonstrated the formation of multiple‐armed single‐crystal Pt nanostructures from tetrahedral seeds through an overgrowth mechanism .…”